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From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	Tom Rini <trini@konsulko.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
	llvm@lists.linux.dev
Subject: [PATCH] kbuild: add $(CLANG_CFLAGS) to KBUILD_CPPFLAGS
Date: Sun,  9 Apr 2023 23:53:57 +0900	[thread overview]
Message-ID: <20230409145358.2538266-1-masahiroy@kernel.org> (raw)

When preprocessing arch/*/kernel/vmlinux.lds.S, the target triple is
not passed to $(CPP) because we add it only to KBUILD_{C,A}FLAGS.

As a result, the linker script is preprocessed with predefined macros
for the build host instead of the target.

Assuming you use an x86 build machine, compare the following:

 $ clang -dM -E -x c /dev/null
 $ clang -dM -E -x c /dev/null -target aarch64-linux-gnu

There is no actual problem presumably because our linker scripts do not
rely on such predefined macros, but it is better to define correct ones.

Move $(CFLAGS_CFLAGS) to KBUILD_CPPFLAGS, so that all *.c, *.S, *.lds.S
will be processed with the proper target triple.

Reported-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/Makefile.clang | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
index 70b354fa1cb4..93ca059cc3b8 100644
--- a/scripts/Makefile.clang
+++ b/scripts/Makefile.clang
@@ -38,6 +38,5 @@ CLANG_FLAGS	+= -Werror=unknown-warning-option
 CLANG_FLAGS	+= -Werror=ignored-optimization-argument
 CLANG_FLAGS	+= -Werror=option-ignored
 CLANG_FLAGS	+= -Werror=unused-command-line-argument
-KBUILD_CFLAGS	+= $(CLANG_FLAGS)
-KBUILD_AFLAGS	+= $(CLANG_FLAGS)
+KBUILD_CPPFLAGS	+= $(CLANG_FLAGS)
 export CLANG_FLAGS
-- 
2.37.2


             reply	other threads:[~2023-04-09 14:54 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-09 14:53 Masahiro Yamada [this message]
2023-04-09 20:09 ` [PATCH] kbuild: add $(CLANG_CFLAGS) to KBUILD_CPPFLAGS kernel test robot
2023-04-10 17:17   ` Nathan Chancellor
2023-04-10 17:25 ` Nathan Chancellor
2023-05-31 21:33 ` Nathan Chancellor
2023-06-02 15:25   ` Nathan Chancellor
2023-06-03 16:32     ` Masahiro Yamada
2023-06-05 15:21       ` Nathan Chancellor
2023-06-06  1:29         ` Masahiro Yamada
2023-06-22 17:06       ` Fangrui Song
2023-06-23  5:40         ` Masahiro Yamada
2023-06-03 16:23   ` Masahiro Yamada

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